Gaskets 1981 z750L

Thank you for your inputs. The bike runs fine no so it`s no point making it worse...

Maybe it will be a good test to check the compression for each cylinder? I had a tool form ebay, but I think it showing incorrect numbers... Let`s say the numbers it good when I do a new test of the compression with a proper tool, can it still be hidden problems in the engine when it comes to the piston and rings? If I delivery the block in for honing and check the rings I will get a better motor
who will run longer than the condition the engine has today?

I mean if the deliver in the block for honing is not excessive, I can do that and then replace the rings? No point to replace the pistons?

When I have taken of the top, can I take photos of the cylinders without taking the block off?
I can turn the engine so each piston are to the bottom for each cylinders and take photos?

Don't misunderstand, I'm not guaranteeing you will make it worse. Everything you touch creates potential an error and additional cost. Not guaranteed but it happens a fair amount of the time to me anyway.
Compression testing is supposed to be done with the engine at full operating temperature. Do so cold will give you some indication of compression but not an accurate one. Cold test would tell you if something is horribly wrong and how much difference in compression between cylinders. A compression test MUST be done with the throttle held wide open to get an accurate reading.
If you can do an operating temperature test with a good gauge and you get a poor result on one or more cylinders. Put a couple of squirts of oil in that cylinder and repeat the test. If the compression comes up significantly (over 10 lbs,) you likely have issues with the rings. If there is no significant change you likely have top end (valve) issues. Best way to tell is a leak down test but doing what I just described will give you a pretty good indication of what is happening.

If there is little to no scoring of the cylinders or pistons you can hone it on your own. If there is any scoring that you can catch with a fingernail it needs to be professionally cleaned up as there is at least .010 inch to catch a nail. Visual inspection will likely tell you.
You must remove the cylinders to install the base cylinder gasket. You will have a clear view of the pistons and the cylinder walls. The visual inspection will likely tell you if you have serious issues or not. Post well lit pics here for verification. You can slowly turn the engine with the cylinders off. I can't stress slowly enough. You are likely to need to move pistons around a bit to get them to drop into the block as the engine rotates. You'll be fine if you don't force anything and you move slowly.

I will see I can get hold of a compression tester before I start, but I think I will just start the work and then take pictures and try to measure the cylinders to see if I can use a flex hone or deliver it to a pro. Then I have a winter project

I would be good to check the compression before I start and after I`m finish with everything also.

Gordone, I got an email update asking the question "Is it required to replace the base cylinder gasket after removing the head?" I do not see it in the string currently. I do not believe the service manual will direct you to do so. Other have reported base cylinder gasket leaks once the head has been pulled off. I cannot say with certainty you should replace the base cylinder gasket. I had a very tiny weeping spot on my KZ650 and opted to do so when I had the head off. I ended up pulling the pan as well because I lost the rubber dampners for the idlers during head removal.

I've use a hold in rubber tipped tester I bought at Farm and Fleet for 13 bucks since 13 with good results........... might be worth it to ya for that to pick one up and check again before you throw the time and cost into it......

I remember double checking the old Sears one (same design) with one I rented for 5 bucks out in the parking lot of a rental place once too (got the same results around 2004.... 29,000 miles) 2 at 150.... 1 at 145 and 1 at 135 that was scored up a little since 1,700 miles when I bought it in 1980.. Got 2 at 155 1 at 150 and the slightly scored up one at 145 when I first bought it.

Got 160 cold before the 1st start and 165 on all 4 after 600 miles so I'm pretty happy with APE's bore and hone job in 2013...... Need to check it again as I've finally just turned over 1,500 miles now.

I have talked with a local workshop about pro. honing, and I`m not blow away of the price he gave me. So I don`t see any big problem delivery the block in for honing. if I understand you all, as longs as I don`t have big scratched will a pro honing job make the the cylinders god as new?

The workshop asked me about the top what I`m going to-do with it? Why is he asking about that? can he also do some honing or something for the valves so they got better ? or is that waste of money?

Background info, these bike is a hobby for me, so when I`m opening up the engine, I don`t want to-do it again for many years, so if I`m going to replace the base gasket / top gasket / valve seals, I can do it proper the first time and not need to open up the engine next year also??

ajsfirehawk:
I just wanted to double check I`m understood you correct, I`m Norwegian so my English has some limitation hear and there
I will replace the base gasket anyway then, said if the motor start leaking from the base gasket after all work how has be done.

I have now tried to go slow through parts diagram and written down the parts I think is maintenance...?
Please see attached PDF, if someone have time to go over will I be grateful

My plan is to get the cylinder and top in good condition, "fresh".

I have also purchase the top gasket you sent ebay link to.